A liquid crystal display (LCD) displays images by aligning a liquid crystal compound in a predetermined direction, and switching the alignment through application of a voltage. A process of manufacturing an LCD is a complicated and high-cost process, and needs a large-scale production line and large-scale equipment.
A polymer dispersed liquid crystal ((PDLC), which is the generic concept encompassing a so-called polymer network liquid crystal (PNCL) and polymer stabilized liquid crystal (PSLC)) element, which is realized by dispersing a liquid crystal in a polymer matrix, has been known. The PDLC is able to be manufactured by coating a liquid crystal solution, and thus can be manufactured by a simpler method than that for a conventional LCD.
As disclosed in Patent Document 1 (Korean Unexamined Patent Application No. 1993-0013794), a liquid crystal compound is not generally aligned in PDLC. For this reason, the PDLC is opaque when a voltage is not applied, and such a state is called a scattering mode. When a voltage is applied to PDLC, the liquid crystal compound is arranged and thus becomes transparent. Therefore, switching between a transparent mode and a scattering mode is able to be performed.
However, since such a PDCL mode exhibits a scattering state in the initial state before a voltage is applied, to maintain transparency, the voltage has to be always applied to a cell, and thus there is high power consumption.